Nice! Sounds great. A3 are really underrated motors. Once you get it dialed in you might want to bump up the gearing a little to keep the rpm down and keep that bushing alive but 45 is pretty damn good for that setup.
You can use marty's gear calculator to figure out your rpm, I would say keep it under 9k, usually that kit doesn't really make much power above 9k so gear to go your top speed at about 8500 and it should be safe.